HOW DO PLANT STEROLS WORK?
- How do plant sterols work in the human body?
- What is the mechanism of cholesterol lowering?
- How much plant sterol spread is needed to reduce blood cholesterol?
- References
Plant sterols partially block the absorption of cholesterol from the intestine reducing the amount that reaches the bloodstream plus any cholesterol consumed in food.
Figure 5: How plant sterols work in the human body
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What is the mechanism of cholesterol lowering?
Plant sterols act by reducing the absorption of dietary and biliary cholesterol from the gastrointestinal tract. During digestion, cholesterol from both sources competes with plant sterols for incorporation into the mixed micelles formed in the gut. Cholesterol predominates because of its higher concentration and is absorbed into the lining of the gut from the micelles. Any cholesterol that cannot be incorporated into the micelles is not absorped and passes out of the gut.
When appreciable amounts of plant sterols are consumed they compete with cholesterol and displace it from the micelles. As a result less cholesterol is absorbed and more is excreted through the bowel (Figure 6). The fall in cholesterol absorption is between 25% and 50%(1). The liver responds to the decreased supply of cholesterol from the gut by increasing uptake of cholesterol from the bloodstream and increasing in cholesterol synthesis. The overall result is a fall in serum total and LDL-cholesterol but no change in triglycerides or HDL-cholesterol.
Figure 6: Mechanism of Action of Phytosterols on Cholesterol Metabolism
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How much plant sterol spread is needed to reduce blood cholesterol?
The amounts of plant sterols consumed in most studies using spreads fall in the range of 1.6 to 3.0g/day. Studies with larger and smaller intakes provide a clear picture of the relationship between plant sterol intakes and a fall in serum LDL-cholesterol to be developed (Figure 7). The figure shows that near-maximal blood cholesterol lowering occurs with an intake of plant sterols of 2g/day. This is equivalent to 25g/day of plant sterol spread. Substantial cholesterol-lowering occurs with a plant sterol intake of half this level. At intakes above 2g/day, further falls in LDL-cholesterol occur but are marginal. Based on these results an intake of plant sterols of 2g/day appears optimal.
Figure 7: Reduction in LDL-Cholesterol Levels with Plant Sterol Consumption
Unilever Studies
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References
- J Jones PJ et al. J Lipid Res 2000;41:697-705.
